For those who’ve not heard of Pentatonix, I wanted to introduce you to them the way I first heard them. Pentatonix is an American a cappella group from Arlington, Texas.
And for those interested, from the Dictionary the word pentatonic means relating to, based on, or denoting a scale of five notes, especially one without semitones equivalent to an ordinary major scale with the fourth and seventh omitted: pentatonic scales in the key of G Major | a simple pentatonic idea repeated chromatically.
This is their video singing The Sound of Silence.